Solution of Coupled Equations by R -Matrix Techniques

A realistic coupled-equation problem is solved using various R-matrix and level-matrix techniques. Comparison with exact coupled-equation calculations shows that excellent numerical results are possible with these methods, both in resonant and in nonresonant energy regions. The effects of varying the R-matrix boundary conditions and the number of levels included in the calculation are considered. Various aspects of R-matrix theory, such as the composition of R-matrix states, and the interference between neighboring levels, are illustrated by the calculations.